Variable Interest Entities (Textual) (Details) - Southern California Edison - VIE	3 Months Ended		12 Months Ended
	Mar. 31, 2019 USD ($) MW	Mar. 31, 2018 USD ($) MW	Dec. 31, 2017 USD ($) $ / shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) $ / shares	Dec. 31, 2013 USD ($) $ / shares	Dec. 31, 2018 USD ($)
SCE Power Purchase Contracts
Variable Interest Entity
Power generating capacity (in megawatts) | MW	4,722	3,454
Payments to unconsolidated VIEs for power purchase contracts	$ 153,000,000	$ 143,000,000
Trust II
Variable Interest Entity
Common stock	10,000						$ 10,000	$ 10,000
Trust II | Trust Securities
Variable Interest Entity
Security dividend rate							5.10%
Liquidation preference	400,000,000						$ 400,000,000	400,000,000
Liquidation value (in dollars per share) | $ / shares							$ 25
Common stock							$ 10,000
Redemption of trust securities	10,000
Trust II | Series G Preferred Stock
Variable Interest Entity
Security dividend rate							5.10%
Liquidation preference	400,000,000						$ 400,000,000	400,000,000
Liquidation value (in dollars per share) | $ / shares							$ 2,500
Trust III
Variable Interest Entity
Common stock	10,000					$ 10,000		10,000
Trust III | Trust Securities
Variable Interest Entity
Security dividend rate						5.75%
Liquidation preference	275,000,000					$ 275,000,000		275,000,000
Liquidation value (in dollars per share) | $ / shares						$ 25
Trust III | Series H Preferred Stock
Variable Interest Entity
Security dividend rate						5.75%
Liquidation preference	275,000,000					$ 275,000,000		275,000,000
Liquidation value (in dollars per share) | $ / shares						$ 2,500
Trust IV
Variable Interest Entity
Common stock	10,000				$ 10,000			10,000
Trust IV | Trust Securities
Variable Interest Entity
Security dividend rate					5.375%
Liquidation preference	325,000,000				$ 325,000,000			325,000,000
Liquidation value (in dollars per share) | $ / shares					$ 25
Trust IV | Series J Preferred Stock
Variable Interest Entity
Security dividend rate					5.375%
Liquidation preference	325,000,000				$ 325,000,000			325,000,000
Liquidation value (in dollars per share) | $ / shares					$ 2,500
Trust V
Variable Interest Entity
Common stock	10,000			$ 10,000				10,000
Trust V | Trust Securities
Variable Interest Entity
Security dividend rate				5.45%
Liquidation preference	300,000,000			$ 300,000,000				300,000,000
Liquidation value (in dollars per share) | $ / shares				$ 25
Trust V | Series K Preferred Stock
Variable Interest Entity
Security dividend rate				5.45%
Liquidation preference	300,000,000			$ 300,000,000				300,000,000
Liquidation value (in dollars per share) | $ / shares				$ 2,500
Trust VI
Variable Interest Entity
Common stock	10,000		$ 10,000					10,000
Trust VI | Trust Securities
Variable Interest Entity
Security dividend rate			5.00%
Liquidation preference	475,000,000		$ 475,000,000					475,000,000
Liquidation value (in dollars per share) | $ / shares			$ 25
Trust VI | Series L Preferred Stock
Variable Interest Entity
Security dividend rate			5.00%
Liquidation preference	$ 475,000,000		$ 475,000,000					$ 475,000,000
Liquidation value (in dollars per share) | $ / shares			$ 2,500